Gluing many faces

The task is a fiber composite cross-section: 200 fibers of radius 0.6 glued into a matrix 30 × 30, so that every fiber and the matrix share the fiber’s outline. The fibers are named fiber and the matrix matrix. For the polygon libraries, the task is to cut the fibers, as polygons of 2048 segments per quarter circle, out of the matrix, which gives the face of the matrix. Figure 1 shows the result of Glue in planex2d and in OpenCASCADE, and Figure 2 the times.

import math
import random
import netgen.occ as occ
import shapely
import planex as px
from comparison_libraries import best, chart, difference

random.seed(2)
L, r, n = 30.0, 0.6, 200
centers = []
while len(centers) < n:
    p = (random.uniform(r, L - r), random.uniform(r, L - r))
    if all(math.dist(p, q) > 2.2 * r for q in centers):
        centers.append(p)

matrix = px.QuickSketch().Rectangle(L, L).Face()
matrix.name = "matrix"
px_fibers = [px.QuickSketch().Circle(x, y, r).Face() for x, y in centers]
for fiber in px_fibers:
    fiber.name = "fiber"
occ_matrix = occ.WorkPlane().Rectangle(L, L).Face()
occ_fibers = [occ.WorkPlane().Circle(x, y, r).Face() for x, y in centers]
polygons = [shapely.Point(x, y).buffer(r, quad_segs=2048) for x, y in centers]

t_px, a = best(lambda: px.Glue([matrix, *px_fibers]))
t_occ, b = best(lambda: occ.Glue([occ_matrix, *occ_fibers]), repeats=1)
others = difference([(0, 0), (L, 0), (L, L), (0, L)], polygons)

matrix_area = sum(f.mass for f in a.faces(name="matrix"))
occ_area = sum(f.mass for f in b.faces)
print(f"planex2d   {t_px:.4f} s, {len(a.faces)} faces, matrix {matrix_area:.6f}")
print(f"OCC        {t_occ:.4f} s, {len(b.faces)} faces, area {occ_area:.6f}")
for name, (t, area) in others.items():
    relative = (area - matrix_area) / matrix_area
    print(f"{name:10} {t:.4f} s, matrix {area:.6f}, relative to planex2d {relative:+.0e}")

planex2d   0.0009 s, 201 faces, matrix 673.805329
OCC        0.0152 s, 201 faces, area 900.000000
shapely    0.8803 s, matrix 673.805351, relative to planex2d +3e-08
pyclipper  0.5844 s, matrix 673.805351, relative to planex2d +3e-08
gdstk      0.6872 s, matrix 673.805351, relative to planex2d +3e-08
manifold3d 0.6687 s, matrix 673.805351, relative to planex2d +3e-08

(a) planex2d

(b) OpenCASCADE

Figure 1: 200 fibers glued into a matrix

* polygon based: only straight lines, curves are approximated by them

Figure 2: Gluing 200 fibers into a matrix